<!DOCTYPE html>
<html>
<HEAD>
<meta charset="utf-8">
<script type="text/javascript" src="../jquery-1.10.2.min.js"></script>
<script type="text/javascript" src="jquery.chained.min.js"></script>
<script type="text/javascript">  
    $(document).ready(function() {  
        $("#series").chained("#mark"); /* or $("#series").chainedTo("#mark"); */  
        $("#model").chained("#series");  
    });  
</script> 
 </HEAD>
 <body>
 
<select id="mark" name="mark">  
        <option value="">--</option>  
        <option value="bmw">BMW</option>  
        <option value="audi">Audi</option>  
    </select>  
    <select id="series" name="series">  
        <option value="">--</option>  
        <option value="series-3" class="bmw">3 series</option>  
        <option value="series-5" class="bmw">5 series</option>  
        <option value="series-6" class="bmw">6 series</option>  
        <option value="a3" class="audi">A3</option>  
        <option value="a4" class="audi">A4</option>  
        <option value="a5" class="audi">A5</option>  
    </select>  
    <select id="model" name="model">  
        <option value="">--</option>  
        <option value="coupe" class="series-3 series-6 a5">Coupe</option>  
        <option value="cabrio" class="series-3 series-6 a3 a5">Cabrio</option>  
        <option value="sedan" class="series-3 series-5 a3 a4">Sedan</option>  
        <option value="sportback" class="a3 a5">Sportback</option>  
    </select>  
</body>
</HTML>
